Along with the development of computer networks and global mobile communication technologies, portable digital processing terminal devices including notebook computers, Personal Digital Assistants (PDAs), computer peripherals, mobile phones, pagers, home electronic appliances, etc., have become necessitates of daily life and office of people. All of the devices possess a powerful processing capability and a larger storage space to thereby form a Personal Operation Space (POS). However, at present, information has to be exchanged between these terminal devices generally through a cable connection, thus causing much inconvenience, and it is increasingly desired for people to connect wirelessly these terminal devices in the personal operation space to truly enable mobile and automatic intercommunication between the terminal devices, which is referred to as wireless multi-hop network technology. In a wireless multi-hop network, data communicated between non-adjacent terminal devices has to be transmitted in a way of multi-hop route.
There are devices playing four roles in a wireless multi-hop network: a terminal device, a route coordinator, a network coordinator and a trusted center. The terminal device can communicate with other devices in the network but can not forward data for the other devices over the network, that is, the terminal device can not perform a routing function. In addition to the function of the terminal device, the route coordinator is also responsible for forwarding data for the other devices in the network, that is, the route coordinator can perform the routing function. The network coordinator is responsible for transmitting a network beacon, setting up a network, managing a network node, storing network node information, searching for a route message between a pair of nodes and continuously receiving information and also can forward data for the other devices in the network, that is, the network coordinator can perform the routing function. The network coordinator and the route coordinator can be referred collectively to as a coordinator. The trusted center is a key management center of the network and is responsible for configuring all the devices in the network with key information. The network coordinator or another device designated in the network by the network coordinator can act as the trusted center. FIG. 1A to FIG. 1C illustrates two network topology structures supported by a wireless multi-hop network: a star structure (as illustrated in FIG. 1A) and a point-to-point network, where the point-to-point network can further be divided into a mesh structure (as illustrated in FIG. 1B) and a cluster structure (as illustrated in FIG. 1C).
For a wireless multi-hop network, security solutions in current use include the following two ones:
A first security solution is in the form of a self-organized network.
A device is firstly connected into a wireless multi-hop network and then acquires key information dynamically from the wireless multi-hop network, e.g., an ID-based private key (identity-based cryptography) acquired from a distributed Certification Authority (CA) in the wireless multi-hop network, and finally uses the ID-based public and private keys for secure communication.
A second security solution is in the form of connecting and then authentication.
Firstly a device is connected into a wireless multi-hop network, then the network coordinator authenticates the device and finally the device uses a negotiated session key for secure communication, e.g., in the standard of IEEE802.15.4/ZigBee.
In the first security solution, any device can be a member of the wireless multi-hop network without distinguishing between legal and illegal devices, which apparently would be insecure. In the second security solution, since the network coordinator does not authenticate the device until the device is connected into the wireless multi-hop network, any devices may be connected into the wireless multi-hop network and communicate with another device in the network before the network coordinator removes it from the network, which also would be insecure and result in a waste of communication.